The primary objective of this trial is to determine if the pharmacokinetic profile of IGIV-C, 5% is comparable to IGIV-C, 10% when used to treat patients with primary humoral immune deficiency who require chronic replacement therapy with intravenous immune globulin, and to compare the two preparations' safety profiles. Intravenous immune globulin (IGIV) is used to treat patients with primary immunodeficiencies, as well as secondary immune deficiencies and autoimmune disorders. Currently, a solvent/detergent (S/D) treated product is widely used. Bayer's Plasma Products Technology Department has developed a new manufacturing process that employs a number of intermediate chromatography steps in the IGIV purification scheme. This chromatography-based process, while maintaining the initial cold ethanol precipitation steps, alleviates a number of labor-intensive and time consuming intermediate centrifuation steps, substituting a more closed chromatographic separation system which reduces the risk of contamination, provides a more gentle treatment of the immune globulin proteins, and yields a final IgG product that is purer and more closely reflects the IgG subclass distribution found in plasma.